Need 1997 3100 upgrade summary

[talon2swords]

I've been reading the posts here. I see some redundancy and it's probably irritating for some of you to repeat the same thing over and over, but I request a summary of the best route to go.

What I have:

A 1997 Chevy Lumina with a 3100 engine

What I want to do:

Increase the performance without replacing the existing heads.

What I think I have read here:

You can take a pre 2000 3100 engine and replace the lower and upper intake manifolds with a post 2000 3100 or 3400 lower intake manifold and a 3500 upper intake manifold and possibly other components as well.

What I'm hazy on:

What gaskets do I have to use and do I need any machine/modification work done (besides the EGR thing) to make the surfaces work correctly.

Sorry if this is newb redundancy, but any help/input appreciated.

[talon2swords]

Yeah, I read some of IsaacHayes stuff (where I got most of the ideas) and looked at his car specs.

Engine:
3.5L DOHC (LX5) 65mm Throttle Body
Ported 3500 (LX9) Upper Intake Manifold
Ported 3400 (LA1) Lower Intake Manifold

Looks like work was done on the manifolds.

I wonder how much power would be picked up just using non modified stock parts. Maybe it's not worth it.

[talon2swords]

Yeah, I read some of IsaacHayes stuff (where I got most of the ideas) and looked at his car specs.

Engine:
3.5L DOHC (LX5) 65mm Throttle Body
Ported 3500 (LX9) Upper Intake Manifold
Ported 3400 (LA1) Lower Intake Manifold

Looks like work was done on the manifolds.

I wonder how much power would be picked up just using non modified stock parts. Maybe it's not worth it.

More from IHs:

"I put 3400 lower intake on my 94 3100, and 3500 upper intake on that, with a 3.5L DOHC throttle body from an olds intrigue.... And this is my one and only car... I did get a large increase in power despite not having roller rockers (had to grind the lower intake to clear them), larger intake valves, and the perfectly match on the heads to the intake manifold. I did not feel like swaping 3400 heads, or 2000+ 3100 heads for those things, since my motor has over 200,000 on it. Doesn't burn any oil though and runs great. The cost in gaskets then would have equaled to what a whole lower mileage 3400 would have cost me. The cost in the intakes added up quick since I had to source them."

[IsaacHayes]

Hi!

Since you have a 1997 you have roller rockers I'm sure. That means no grinding on the LIM to clear the old style rockers. The later year 3100/3400 intakes are better in the way they are cast. Check out the WOTTECH banner they have pics and explanation. I grabbed a 97 LIM from a 3400 however as it was already tapped with the 3/4" or whatever it is NPT for the coolant pipe. The later years are press in with an oring and bracket to hold it in. I didn't feel like adapting to that like some do, or buying a tap (harbor frieght has them cheap though), so I went with the 97, which doesn't have quite as good of casting as say an 03 one...

Anyway, you want to go to large port intakes, which means 3400 or 2000+ 3100. Now for the upper, you can go with a 3400 96-99 and that will bolt up to your EGR, but it does not flow that great in the neck area due to a bulge there, as the 2000+ 3100/3400 uppers. But they changed the EGR mount in 2000+ so you would need a 2000+ EGR, and the tube that goes to the EGR. That would bolt up and connect to your stock electrical connector and work just fine. They just changed how it fits/style not the function.

Then use a 3400 TB as they are 56mm instead of the 52mm on the 3100's. If need be you can remove the shaft and swap over your linkage to the 56mm TB and plate.

Or you can go my route and get a 3500 upper, and 65mm TB. The billet units WOT sells bolt up like stock where the LX5 TB requires you to chop the top of the throttle bracket and attach it some how to the TB. Some have just drilled and tapped the arm on the TB that has the throttle stop and put a bolt there through the bracket, and I opted to bend some small stainless and have a friend TIG it to the bracket and bolt it to the TB's place where the TB bracket normally bolts to. The bottom bolt on the bracket bolts up like normal to the bottom bolt of the TB. Either TB you need an adapter. LX5 you need the TB gasket (there are two, make sure you get the right one from parts store), and then a custom gasket (single layer paperboard works) for the adapter to plenum, alllthough I think the new adapters use an o-ring. For the billet the adapter works with o-rings. If you use a 3400 TB with the adapter you need a cardboard gasket cut too as the stock won't seal everything its' too small.

I had to get creative with the air cleaner tube. Since mine is a 94 without MAF, I grabbed an air tube from a MAF car which is shorter (has maf in between air box) and used that. Otherwise it's smashed as the 3500 plenum and the LX5 TB both move the TB closer to the air box.

Also with the 3500 plenum there is a few other minor mods, vacuum lines, 3500 MAP (if you want to use it) to get it going. But it's nothing crazy. Mine all looks factory and is painted up nice. People at first think it has an engine cover on it until they realize it's the actual manifold it's that nice.

Anywho, that about covers it. Use the metal felpro or dorman LIM gaskets for the 97 3100. You will have to get a 3400 upper intake gasket separately ($4).

Porting is not necessary, but I figured since I have them in my hand, might as well make the most of my effort. Porting the 3500 upper was easy since it has no runners, but it needed the most opening up on the ports as it was smaller than the 3400 gasket by a decent bit. The 3400 lower wasn't too bad, just touched it up on a few spots and blended those areas down about an inch or so. I just wanted smooth flow and no transition differences. I didn't hog them out or anything. Just going to the large port stuff was a huge size increase that you can't do with porting the small port stuff. I left the bottom ports alone since I wasn't taking off the heads to match them too. 3400 upper ports should be closer to the 3400 gasket I'd think since the lower was. The 3500 is slightly smaller but there is more to it than just flow like velocity. I could have thrown it on un-ported and it would have worked fine, since it would have been small hole going into a large hole so it wouldn't be hitting a shelf with the flow, but I wanted it to not be interrupted on it's flow by expanding suddenly which could slow velocity and also affect the resonance of the pulses coming back up.

Hope that helps.

Oh and open up the exhaust. That's what I'm doing in spring and will REALLY let these mods work well. My exhaust stock is extremely restrictive. Not sure how the W bodies are. I've got 2.5" stainless mandrel bent to put on hehe woo wooo!

[talon2swords]

Hi!

Since you have a 1997 you have roller rockers...

Wow, thanks for the quick and detailed reply. I had some extra time so I went to the local pick and pull place.

They have some later model 3100/3400 parts there (not much, but some).

I saw a 99 model 3400 upper and I was wondering if that would work, since it looked like a early 3100 at the EGR (I didn't see any 3500's out there, so I may just get the larger 3400/later3100 for now-depending).

Anyhow your explanation will help me decide which parts to get.

I asked the parts guy what he charges, and he just pulled a figure out of his head of 60 bucks for upper and lower. I guess that's fair, seems cheap to me for the potential performance.

Anyhow thanks again!

[Monzsta]

Good luck. A fellow Luminatic.

[IsaacHayes]

99 UIM wont flow as good as 2000+ stuff. But yes will work with your EGR without changing to the new one. BTW 3500 UIM has same EGR as 2000+ 3x00 too. So 96-99 3400 UIM ok, 2000+ better, 3500 (LX9 one) best. Also the later year LIM's flow better too due to better casting (less injector bulge, better top angle/transition)

60 for both is a good deal.

Check www.car-part.com for prices too and call some places and find out how much shipped they would be. But you cant beat 60 for both. If you could get 2000+ both for 60 and then a little more for the EGR adn EGR tube I'd do that. Or maybe just lower and find a 3500 UIM on car-part. But locally sounds pretty good to me, they sound like they have fair prices.

[talon2swords]

99 UIM wont flow as good as 2000+ stuff. But yes will work with your EGR without changing to the new one. BTW 3500 UIM has same EGR as 2000+ 3x00 too. So 96-99 3400 UIM ok, 2000+ better, 3500 (LX9 one) best. Also the later year LIM's flow better too due to better casting (less injector bulge, better top angle/transition)

60 for both is a good deal.

Check www.car-part.com for prices too and call some places and find out how much shipped they would be. But you cant beat 60 for both. If you could get 2000+ both for 60 and then a little more for the EGR adn EGR tube I'd do that. Or maybe just lower and find a 3500 UIM on car-part. But locally sounds pretty good to me, they sound like they have fair prices.

Oh, I didn't know this post had another response. Again thanks for the extra info.

I had a bad, somewhat embarrasing experience here at the local pick and pull last weekend.

The day before I had scouted the yard for the parts. I found a donor car and I went to the front counter to get a price quote. I always seem to get the "confused" employees to help me.

I specifically asked her the price for BOTH the upper and lower intake manifold together. She tapped the keyboard a few times but eventually gave up and asked the guy standing next to her to help her. He asked what I wanted, and I told him and again a I tried to spell it out to him. He eventually kinda shrugged his shoulders and said "60 bucks." I left the site, went home.

The next day I decided to go get my parts. I went in and used up about 1.5 hours or so setting up and pulling the stuff off the car (guess I'm a little slow).

It started to rain, but I finally got the parts I needed. I went to the counter. Of course the employees were different on this day, and the guy that waited on me started saying "60 bucks...each." In other words, they now wanted 120bucks for both pieces.

I had left the throttle body and injectors on the assembly thinking I could pay a little extra for that or take it off real quick if I had to(like I said, had been raining). The price started going in the 200+ range.

Then the guy started getting smart and said " you'd be better off getting the whole engine." Well, first off, at this place, I don't even know if the engine is broken or not. No way I'm buying a broken engine. They don't keep inventory. Second, I don't want the whole engine, I just want a few parts.

I was wet and pissed off, so I just left the parts there and walked away. I'll never do business with a another pick and pull place unless I get a parts quote in writing first with a signature.

Anyhow, thanks for the link. I may do some more research on pricing, etc. before I make another mistake.